In this project bacteria and steam were tested to stimulate limestone cores damaged by asphaltene deposition. Several dynamic experiments were conducted to determine the effect of asphaltene on the permeability of limestone cores. Plugging effects due to asphaltene deposition were evaluated through a comparison between permeability measurements after oil flow and the reference permeability measured prior to oil flow. Damaged cores were subjected to bacteria and/or steam and the permeability of the cores was measured after each treatment. Core impairment resulting from in-situ asphaltene deposition was found to cause a 56 to 89% loss of initial oil permeability depending on rock permeability and injection rate. Core stimulation results from direct bacteria treatment, was found to cause a 3 to 105% improvement on the damaged core permeability depending on core permeability and the extent of the damage. Bacteria treatment results were compared to steam treatment of the damaged cores.

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